Collet chuck



April 1952 E. L. DEVIS ETAL 2,592,794

COLL-ET CHUCK Filed on. 16, 1948 2 SHEETS-SHEET 1 INVENTORSZ' M yanks.

THEIR ATTORNEYS.

April 15, 1952 E. L. DEVIS ETAL COLLE'I' CHUCK 2 Sl-IEETS-SI-EET 2 Filed Oct. 16, 1948 INVENTORS.

THEIR ATTORNEY Patented Apr. 15, 1952 UNITED STATES PATENT OFFICE 2,592,794 COLLET CHUCK Earl L. Devls and Charles E. Unkefer, Canton,

Ohio, assigno'rs to The Timken Roller Bearing Gompany, Canton, Ohio, a corporation of Ohio Application October 16, 1948, Serial No. 54,874

2 Claims (01.279-61) l Our invention is concerned with a collet chuck for holding the work in lat-hes, boring mills and other machine "tools during the performance of machining operations.

It is a principal obj ect of this invention to provide a chuck composed of relatively few parts and capable of ready assembly.

Another object is 'to provide a spring collet chuck with a back-up ring to position the work piece axially in the collet sleeve, procuring a more certain and easy alignment between these parts.

A further object of this invention is to provide a collet chuck in which the gripping action of the collet spring fingers does not affect the relative alinement of the axes of the work piece and the collet sleeve or the initial axial setting of the work piece.

With the above and other objects in view the presentinvention consists in the combinations and arrangements of parts hereinafter more fully described, illustrated in the accompanying drawlugs and particularly specified in the appended claims.

In the accompanying drawings, which form part of this specification and wherein like symuols refer to like parts Wherever they occur,

Fig. l is a central longitudinal sectional view showing our collet chuck mounted on the rotary spindle of a machine tool, the collet chuck being shown in closed position,

Fig. 2 is a fragmentary section similar to Fig. 1, showing the collet chuck in open position,

Fig. 3 is a fragmentary transverse sectional view on the line 3-3 in Fig. 1,

Fig. 4 is a fragmentary transverse sectional view on the line 44 in Fig. 1,

Fig. i 5 is an outer end elevational view of the spring collet,

Fig. 6 is a central longitudinal sectional View on the line 5-45 in Fig. 5,

Fig. 7 is a central longitudinal sectional View of the collet sleeve,

Fig. 8 is an outer end elevational view of the back-up ring; and

Fig. 9 is a longitudinal section on the line 99 in Fig. 8.

In Figures 1 and 2, numeral I represents a collet sleeve of cylindrical conformation. The collet sleeve'l has an axial socket 2, also of approximately cylindrical conformation. One end of said axial socket 2 is closed by base 3 of collet sleeve I. The opposite end is open, terminating in iiared mouth-forming a conical inside collet surface 4. The base 3 is pierced by an axial bore 6 which communicates with the axial socket 2, The collet sleeve I is provided with radially disposed set screws 1 through its cylindrical wall 8. The cylindrical wall 8 is provided with longitudinal guide slots or grooves 9,f n the inner surface thereof, Whose end walls I0 are disposed radially, i. e., perpendicular to the longitudinal axis of said socket. The spring collet II is roughly cylindrical in design. The spring collet is rovided with a circular series of longitudinal slots 12, forming gripping fingers It. The-fingers I3 are joined to base or inner end portion of spring collet I I, by means of thin spring portions IE. The spring work gripping fingers I3 are tapered from their outer ends to their thin inner end portions I5 in conformity with the conical inside *su'rfaee 4, forming a conical outside collet surface I6. Into base portion or member hlj'of collet II is fitted a draw rod I? by means of screw threads or equivalents thereof. I

In Figure 1 the rotary hollow spindle I8 of a conventional machine tool is'represehted. Threadably disposed on spindle I8 is an adaptor I9 provided with an axial socket 20 and set screws 2|. The spindle l8 and adaptor I9 together comprise the collet-holder.

The collet chuck also includes a back-up ring 22 having a circular series off'rad-ially disposed out standing longitudinal lugs 23 on its outer 'periphery. Said radial lugs are provided with chamfered end edges 24 that are engaged by the conical ends of said set screws 1. The work piece is indicated by numeral 25.

In operation the collet sleeve I is placed in the adaptor socket 20 of the adaptor I9. The set screws 2i of the adaptor I9 are tightened fixing the collect sleeve I in position in the collet-holder.

The spring collet II is then fitted into the axial socket 2 of the collet sleeve I. In this position, the conical outside collet surface I6 of collet i I lies against and within the conical inside collet surface 4 of collet sleeve I. The gripping fingers i3 of the collet II are thus contained within the conical mouth 4 of collet sleeve I. The base member I4 of said collet lies adjacent and parallel to base 3 of the collets'leeve. Draw rod I1 projects through and beyond bore 6 of said base 3 and through the hollow rotary spindle I8 of the collet-holder.

Next the back-up ring 22 is placed within the spring collet II. In order to accomplish this, the radial lugs 23 of said baok -up ring '22 are slidably disposed in the slots I2 cfthe spring collet II, through which they projectifadially. The length of said lugs is such that they rest in the longitudinal guide grooves II) of collet sleeve I.

Back-up rin 22 is moved inwardly toward the base 3 of collet sleeve I until its integral radial lugs 23 seat against the radial abutments III at the inner ends or the guide slots 9 for said lugs. When the back-up ring 22 reaches this position, the set screws 1 in the wall 8 of collet sleeve l are tightened against the chamfered ends 24 of said radial lugs. Tightening of the aforesaid set screws 1 fixes the back-up ring 18 rigidly with respect to collet sleeve I The work piece 25 is then placed within the spring collet H. t is slipped into the circular opening formed by the gripping ends of the fingers l3 of said collet. The work piece is pushed further within said collet until its movement is stopped by the now rigid back-up ring 22. The function of the back-up ring 22 is to supply support to the work piece 25 so that it will :be secureagainst inward movement along the longitudinal axes ofthe spring collet H and its associated collet sleeve I.

The draw rod I! is then moved to the left in Figure I. Said draw rod must be supported at its left end with respect to the collet sleeve I and rotary spindle it. Such support may be accomplished by a nut or any suitable equivalent.

Movement of the draw rod to the left will sufiice to force conical surfaces 4 and I6 of the collet sleeve l and collet ll, respectively, into spring opposition. As the draw rod l1 moves to the left, thegripping fingers i3 of the collet ll will be forced radially inwardly toward the longitudinal axis of the spring collet. As the gripping fingers l3 move radially a gripping force is provided to secure the work piece 25 against radial movement relative to said longitudinal axis of said spring collet.

The work piece 25 may be removed by reversing the aforesaid movement of the draw rod [1. The conical collet surfaces 4 and It will be withdrawn from spring opposition and the spring fingers 13 of the collet II will release their grip upon the work piece.

It will be noted that neither the movement of the spring collet H to the left with respect to both the collet sleeve i and the back-up ring 22 nor its resultant eiiect, the radial movement of the gripping fingers 13 has any effect upon the longitudinal setting of the work piece 25 within the collet sleeve and against back-up ring 22.

4 By varying the depth of the back-up ring it is possible to accommodate various positionings of the work piece within the chuck.

What we claim is:

1. In a chuck, a collet sleeve closed at its inner end forming a socket and open at its opposite end in a mouth having an outwardly flared sur face, said sleeve having axially directed guide grooves in its inner surface extending through said flared mouth and terminating adjacent said sleeve socket, a collet disposed in said sleeve, said collet having a base movably located in said sleeve socket and a plurality of integral, axially extending and circumferentially spaced fingers, said fingers having outer tapered surfaces engageable with and slidable relative to said flared surface of said sleeve mouth and inner spring portions adjacent said collet base, a collet draw rod extending through said sleeve at its closed inner end for connection into said collet base. and a work back-up ring having a plurality of radial lugs movable inwardly through said sleeve mouth between said spaced collet fingers in said collet sleeve guide grooves for location against the inner ends of said guide grooves.

2. The chuck set forth in claim 1, whereineach of said work back-up ring lugs has a chamfered end, and set screws carried in said collet sleeve engage said lugs chamfers to secure said back-up ring lugs against the inner ends of said guide grooves.

EARL L. DEVIS. CHARLES E. UNKEFER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Brownlee Mar. l, 1919 

